How to close db connection

[malik ge]

Hi,
I am making a small application. I have a separate class which inserts or gets the data from database.
I want to know how to close the connection of database?

Should I do con.close(); in every method or closing the connection in finalize() method is sufficient?

public class DatabaseClass
{
    private Connection con;
    
    //no argument constructor
    public DatabaseClass throws ClassNotFoundException , SQLException
    {
        establishConnection();
    }
    
    
     //establish connection method
    private void establishConnection() throws ClassNotFoundException , SQLException
    {
        
         Class.forName("com.mysql.jdbc.Driver");
         String conUrl = "jdbc:mysql://localhost/databaseName?user=root&password=root";
         con = DriverManager.getConnection(conUrl);
    }

////////////////////Method 1//////////////////
    public void updateUser(InfoBean info) throws SQLException    
    {
        String sql = "Select * from someTable where name=? ";
        
        //some statements...
        pStmt.executeUpdate();
        
    }
////////////////////Method 2//////////////////
    public void updateUser(InfoBean info) throws SQLException    
    {
        String sql = "Select * from someTable where name=? ";
        
        //some statements...
        pStmt.executeUpdate();
        
    }

//////////////////Finilize method//////////////////
    public void finalize() throws Throwable
    {
        super.finalize();
        try
        {
            if(con!=null)
            {
                con.close();
            }
        }
        catch(SQLException e)
        {
            System.out.println(e);
        }
                
    } 

[Hebert Coelho]

I would do con.close(); for every action, not method.

If you need to use the database 3 times for an action you would open and close just once. If you do 3 times your performance will decrease.

[malik ge]

I didn't get what you meant by

do con.close(); for every action, not method.

[Hebert Coelho]

malik ge wrote:I didn't get what you meant by

do con.close(); for every action, not method.

Let us supose you have a method that will create a customer, a car and a house.

An action would be something like:

openConnection();
createCustomer(customer);
createCar(customer);
createHouse(customer);
closeConnection();

An action would be like group of methods.

[Philip Grove]

Splitting the con.close() invocation out into its own method gives the risk of forgetting to invoke that method, but at the same time opening and closing the connection provides overhead so doing it as few times as possible is generally a good idea.

Do not use the finalize() method for housekeping. They are meant for objects holding native resources, and while a connection is a native resource there is also no guarantee that they will ever run.